I don't have much faith in killing power formulas in general. Most are obviously designed to reinforce someone's pre-conceived notions. I was curious to see what the results would look like if I included the most obvious, easily quantifiable, factors in a simple killing power formula. These factors are velocity, energy, bullet weight, sectional density (SD) and bullet cross-sectional area.

After some thought and some time spent playing around with those numbers on my hand calculator, I found that if I took energy at 100 yards and multiplied it by bullet sectional density (a fractional number) and bullet cross-sectional area (also a fractional number), the result was a manageable two or three digit number, which I then rounded off to one decimal place. Ergo, the killing power number.

I choose energy at 100 yards, because most Class 2 to Class 4 game is killed between 50 and 150 yards. 100 yards is right in the middle of that spread and energy at 100 yards is included in most ballistics tables, so it's an easy number to use.

In addition, 100 meters is only slightly longer than 100 yards, so for all practical purposes the same killing power results will apply at 100 meters as well as 100 yards. If you want to compare the killing power of cartridges at some other distance, just plug-in the energy figures for that distance and work the equation.

The most important factor in killing power, by far, is bullet placement. The second most important factor is probably bullet terminal performance. The third most important factor is probably the physical and mental state of the game animal in question at the moment it is shot. This formula takes into account none of those factors.

Unfortunately, those key factors are not quantifiable, at least by me. Therefore, I am assuming that the hunter knows how to shoot, where to put the bullet, and that the bullet is appropriate for the game and conditions.

I will say that after I had initially calculated the results for a number of common rifle cartridges using the formula above, I was encouraged. The results seemed reasonable in light of my personal research and experience. I concluded that, although undoubtedly not perfect, these killing power scores generally have a positive correlation with reality. I would suggest that a 100 yard Killing Power Score of at least 12.5 is required for hunting Class 2 game (deer, pronghorn, sheep, goats, etc.).

Remember that these scores are the result of an attempt to apply a simple formula to an extremely complex problem. Unlike the creators of "pounds-feet," "impulse energy," "hydro-static shock" and other pseudo scientific terms, I want it to be clearly understood that these killing power scores do not represent any scientific quantity or unit of measurement. Use them as an indicator as seems appropriate, but do not attempt to make them into some sort of killing power dogma.

The list that follows is intended to suggest the relative killing power of various hunting cartridges and loads at 100 yards when those cartridges are used appropriately. (Cartridge, bullet weight in grains, muzzle velocity in feet per second - killing power score at 100 yards.)